1. Field of the Invention
The present invention pertains to a liquid fifth wheel assembly for use in conjunction with tractor-trailer combinations and, more particularly, to a dual concentric suction and discharge pipe structure in a liquid fifth wheel assembly that is positionally secured to the underside of a trailer and which liquid fifth wheel assembly need not be removed when separating the trailer and the tractor.
2. Description of the Prior Art
Heretofore, fifth wheel assemblies for connecting tractors and trailers have almost universally employed king pin connections. In cases where a liquid fifth wheel has been required, it has been necessary to dismantle the fifth wheel assembly in order to disengage the tractor from the trailer. The necessity of disassembling the prior art liquid fifth wheel assemblies to disengage the tractor from the trailer has required much time and accompanying expense along with the increased propensity for damaging the parts of the liquid fifth wheel assembly due to the constant assembling and disassembling thereof.
There are several issued U.S. Patents which pertain generally to subject matter comprising the present invention. For example, U.S. Pat. No. 3,711,122 granted to Holmberg et al. discloses a tractor semi-trailer coupling mechanism in which the coupling member secured to the tractor comprises a hollow locking bolt and the king pin in the coupling member secured to the semi-trailer is hollow for engagement of the locking bolt in the king pin or vice-versa, the hollow king pin in at least an upper portion thereof being adapted to receive a connector member with connecting means for electrical power lines, pneumatic power lines and/or hydraulic lines leading from the tractor to the semi-trailer. The hollow locking bolt comprises a connector member complimentary to the first connector member and having connecting means for feed lines from the tractor to the semi-trailer. As it pertains to the present invention Holmberg et al. teach the use of two airlines extending through the fifth wheel. However, as will be apparent from the following disclosure, the Holmberg et al. patent does not disclose or suggest the subject matter of the present invention.
Another example of the prior art is disclosed in U.S. Pat. No. 3,888,513 granted to Pilz et al. This second U.S. patent teaches a service line coupling arrangement by which air and electrical service lines of the tractor are coupled to corresponding air and electrical servical lines of a trailer upon movement of a tractor into drivable interconnection with the trailer. More particularly, the Pilz et al. patent discloses mating male and female service line coupling members which are mounted one on the tractor and one on the front wall of the trailer for movement into mating interengagement when the tractor and trailer are moved into coupled interconnection. The coupling member carried by the tractor is connected to the air and electrical supply lines of the tractor, and the coupling member carried on the front wall of the trailer is connected to points of delivery of the air or electrical power, such as the air brake units and the lights of the trailer. Therefore, when the male and female coupling members are moved into mating engagement the supply lines of the tractor and the trailer are interconnected independently of any manual coupling operation on the part of the driver of the tractor.
In the Pilz et al. patent, the service line coupling member mounted in the tractor is supported for pivotal movement in opposite directions with respect to the axis of the fifth wheel on the tractor and is further supported for reciprocating movement radially of the fifth wheel axis. The pivotal and reciprocating capability of the coupling member facilitates orientation of the coupling member relative to the mating coupling member on the trailer wall during movement of the tractor into interengagement with the trailer. It will be appreciated that the Pilz et al. patent which discloses multiple passageways extending through the coupling members does not patentably anticipate the present invention.
Another excellent example of the prior art in the field to which the present invention is directed is U.S. Pat. No. 3,598,427 which was assigned to the assignee of the present application. In the prior issued U.S. Patent there is disclosed an improved fifth wheel assembly for a tractor and trailer combination which is substantially entirely secured to the front underside of the trailer during separation and connection of the trailer and the tractor and during operation of the tractor and the trailer combination. The fifth wheel assembly includes means disposed on the tractor which are adapted to receive the fifth wheel assembly that is secured to the underside of the trailer in bearing engagement. Means are further provided for positionally securing the fifth wheel assembly on the underside of the trailer with respect to means disposed on the tractor which receives substantially none of the shear forces that are presented to the fifth wheel assembly. In the prior issued patent, the fifth wheel assembly which is secured to the underside of the trailer comprises upper and lower mounting plates, an annular ball bearing assembly disposed between the mounting plates and secured therebetween, a subframe member having an upper mounting bracket secured thereto and descending therefrom and adapted to be placed in bearing engagement with a lower mounting bracket secured to the tractor. A central opening is provided in the entire assembly through which passes an enclosed pipe structure that inter-connects the tank and the pump station with the pipe structure including a swivel joint for permitting limited angular displacement of one portion of the pipe structure housing.
There are many advantages to the construction disclosed in the aforementioned U.S. Patent. Initially, direct transmission of liquids from the tank to the product pump on the tractor is permitted. The need for overhead jumper hoses or trailer hose connections is obviated and pump suction problems are minimized while at the same time pump life is extended.
In spite of the foregoing advantages, it has been found that several improvements can be made in the construction exemplified by the aforementioned U.S. Patent. For example, in the previously issued U.S. Patent a single swivel joint was used for suction purposes from the tank to a pump on the vehicle tractor. The discharge from the pump, was piped to and through filtration, metering and dispensing equipment on the tractor. Due to the limited space on the tractor, usually a discharge hose was run as a jumper hose from the tractor to the trailer wherein the filtration metering and dispensing equipment was more conveniently arranged. However, the jumper hose was subject to damage and deterioration. It is to improvements along the foregoing lines that the present invention is directed. For example, and as will be explained more fully hereinafter, the present invention utilizes a dual concentric swivel wherein both suction and discharge can be ducted through the center of the fifth wheel. The ancillary equipment for filtration, metering, pressure controls is on the trailer in any convenient arrangement and location.